Key term
Edexcel GCSE Physics 1PH0
Key Concepts of Physics
Motion and Forces
Topic overviewScalar and vector quantitiesExamples of vectors and scalars, and velocitySpeed, distance, time and distance-time graphsAcceleration and the equation v squared minus u squaredVelocity-time graphs and free fallMeasuring speed in the laboratory, and typical everyday speedsNewton's first law, and investigating force, mass and accelerationNewton's second and third lawsWeight, mass and gravitational field strengthCircular motion and centripetal forceInertial mass and momentumCollisions, and force as the rate of change of momentumReaction time, stopping distance and large decelerationsFactors affecting stopping distance and reaction timeBraking distance, speed and work done
Conservation of Energy
Waves
Topic overviewWhat waves transfer, and the evidence for itFrequency, wavelength, amplitude and periodLongitudinal and transverse wavesThe wave equationMeasuring wave speed, and what happens at a boundaryMeasuring waves, and calculating depth from wave velocityReflection, refraction, transmission and absorption at a boundarySound waves, ultrasound and infrasoundUses of ultrasound and infrasound
Light and the Electromagnetic Spectrum
Topic overviewReflection, refraction and total internal reflectionWhy objects appear colouredLenses, ray diagrams and imagesProperties of electromagnetic wavesInvestigating refraction in glass blocksThe groups of the electromagnetic spectrumThe continuous spectrum, and what our eyes can detectAbsorption, transmission and the velocity of electromagnetic wavesEmitting and absorbing thermal radiationConstant temperature and the temperature of the EarthHow radiation is generated, and why danger rises with frequencyHarmful effects of excessive exposure to radiationUses of electromagnetic radiation
Radioactivity
Topic overviewThe atom and the size of atomsIsotopes, atomic number and mass numberRelative masses and charges of subatomic particlesElectron orbits and energy levelsForming ions, and how the atomic model changedTypes of ionising radiationBackground radiation and detecting radioactivityAlpha, beta and gamma, and their penetrating powerBeta-minus and beta-plus decayEffects of decay on atomic number and mass numberBalancing nuclear equationsActivity and the becquerelHalf-life and the randomness of decayHalf-life calculationsUses of radioactivity, and how danger depends on half-lifeThe dangers of ionising radiationSafety precautions, contamination and irradiationRadiotherapy, medical tracers and PET scannersNuclear power and where nuclear energy comes fromFission of uranium-235 and the chain reactionControlling a reactor and generating electricityNuclear fusion and how it differs from fissionWhy fusion needs extreme conditions
Astronomy
Topic overviewWeight and gravitational field strength on other bodiesThe Solar System and the order of the planetsHow ideas about the Solar System and ways of observing it have changedOrbits of moons, planets, comets and satellitesGravity, orbital speed and stable orbitsThe Steady State and Big Bang theoriesEvidence for an expanding UniverseThe Doppler effect and red-shift in galaxiesThe life cycle of a star like the SunThe life cycle of stars more massive than the Sun
Energy – Forces Doing Work
Topic overviewEnergy stores and energy transfer diagramsChanging a system's energy, and measuring work doneWork done and the energy changes it causesGravitational potential and kinetic energy calculationsDissipation and wasted energyPower as the rate of energy transferThe watt, and calculating efficiency
Forces and Their Effects
Electricity and Circuits
Topic overviewThe atom, and drawing circuit diagramsSeries and parallel circuitsPotential difference and the voltmeterEnergy transferred by moving chargeCurrent, charge and measuring currentResistance and the equation V = IRResistors in series and in parallelDesigning circuits to test componentsInvestigating resistance in circuitsCurrent-potential difference graphs for componentsLight-dependent resistors and thermistorsThe heating effect of an electric currentUses of the heating effect, and the equation E = IVtPower as energy transferred per secondCalculating electrical powerEnergy transfer in domestic devices, and power ratingsDirect and alternating currentAlternating current and the UK mains supplyLive and neutral wires, earthing and fusesFuses in the live wire, mains voltages and electrical dangers
Static Electricity
Magnetism and the Motor Effect
Topic overviewMagnetic poles, permanent and induced magnetsUses of magnetic materialsThe magnetic field around a bar magnetPlotting compasses and the Earth's magnetic fieldThe magnetic effect of an electric currentSolenoids and electromagnetsThe motor effect and Fleming's left-hand ruleThe force on a conductor, and how a motor turns
Electromagnetic Induction
Topic overviewInducing a current by moving a magnetFactors affecting an induced potential differenceAlternators and microphonesHow a transformer worksThe transformer turns-ratio equationThe national grid, and step-up and step-down transformersTransformer power calculationsWhy high-voltage transmission reduces energy loss
Particle Model
Topic overviewKinetic theory and differences in densityCalculating density, and investigating itChanges of state and internal energySpecific heat capacitySpecific latent heat and thermal insulationInvestigating the specific heat capacity of waterGas pressure and the motion of particlesAbsolute zero and the kelvin scaleCompressing gases, and the force a gas exertsPressure and volume of a fixed mass of gas
Forces and Matter
Topic overviewElastic and inelastic distortionSpring constant, and linear and non-linear behaviourWork done in stretching a springAtmospheric pressure and pressure in a fluidForce, area and pressureCalculating pressure, and how pressure varies with depthPressure in liquids: density and depthUpthrust, floating and sinking
Motion and Forces
Circular motion and centripetal force
- 3 things to know
- Paper 1
Overview
Why velocity changes in circular motion at constant speed, what a centripetal force is and where it acts, and gravity, friction and tension as the forces providing it.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
A ball on a string is whirled in a horizontal circle at a steady rate. Describe how its velocity changes.
Key term
Explain why an object cannot move along a circular path unless a resultant force acts on it.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Explain why an object moving in a circle at a constant speed has a changing velocity.
Model answer
Its direction of motion changes continuously, and velocity depends on direction as well as on speed.
- 2
A satellite orbits the Earth at a steady speed. State whether its velocity is constant and give a reason.
Model answer
Its velocity is not constant, because the direction of travel keeps changing.
- 3
Is an object moving around a circular path at constant speed accelerating? Explain your answer.
Model answer
Yes, because its velocity changes direction, and any change of velocity is an acceleration.
- 4
A car drives around a roundabout at a steady 8 m/s. Compare its speed and its velocity during the turn.
Model answer
The speed stays at 8 m/s, but the velocity changes because the direction changes.
- 5
A ball on a string is whirled in a horizontal circle at a steady rate. Describe how its velocity changes.
Model answer
The magnitude of the velocity stays the same while its direction changes at every point of the circle.
- 6
What is meant by a centripetal force?
Model answer
It is the resultant force acting towards the centre of a circular path.
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